Shrapnel sonar

ABSTRACT

The invention provides an unique hand held device including a rotating transducer generating two high frequency signals which cause a nonlinear liquid to generate a low frequency signal which is then projected thru the liquid medium and a low pass filter in such a way as to direct the low frequency sound signal into animal tissue for the purpose of detecting foreign bodies located therein thru a return echo that is displayed on a cathode ray tube mounted in the device.

iliiited States Patent Muir Oct. 2, 1973 1 SHRAPNEL SONAR PrimaryExaminer-Richard A. Farley [75] Inventor: Thomas G. Muir, Austin, Tex.Atmmey*R' sclascla et [73 Assignee: The United States of America asrepresented by the Secretary [57] ABSTRACT of the Navy' The inventionprovides an unique hand held device in- [22] Filed: Sept. 21, 1972eluding a rotating transducer generating two high frequency signalswhich cause a nonlinear liquid to gener- [21] Appl 29ll53 ate a lowfrequency signal which is then projected thru 52 us. Cl. 340/1 R 73/67.?340/3 R the quid medium and 3 Pass film Such a way 511 int. Cl. (501s9/66 as to direct frequency Smmd Signal animal [58] Field of Search j340/] R 3 tissue for the purpose of detecting foreign bodies 10- l i I Ii cated therein thru a return echo that is displayed on a cathode raytube mounted in the device.

[56] References Cited 8 Claims, 3 Drawing Figures UNITED STATES PATENTS3,613,069 10/1971 Cary, Jr. et a1. 340/3 R SI-IRAFNEL SONAR Methods fordetection of foreign bodies in animal tissue are the X-Ray technique andechoencephalographic techniques. Although X-radiation offers a precisemethod for the location and mapping of foreign bodies, it is potentiallydangerous to living cells and it requires the use of large, bulkyapparatus as well as photographic processes that are not commensuratewith field operations involving ground forces or with operations on thehigh seas, except on capital ships. The advent of echoencephalographictechnology has raised great hopes for an alternative technique. By usingultrasonic radiation in the linear sense, physicians in a few largehospitals have been able to locate objects and structures in animaltissue. The limitations of this method are that to achieve the desiredpenetration, a relatively crude, low frequency mode of operation must beused; and secondly to electronically store and scan the acquired echodata, a complex logic system is required. Low operating frequencies leadto systems with poor resolution, thereby degrading the accuracy andquality of the detection system. Signal processing techniques have beenused to minimize this difficulty but the end result is usually anechoencephalographic system that has to be focused. Focusing leads toresolution limitations brought about by the finite depth of field.Moreover, high speed scanning of both focused and unfocusedechoencephalographic systems requires the use of large, on-linecomputers which are not amenable to field use.

It is therefore an object of this invention to provide an improveddevice for locating foreign objects in animal tissue.

It is still a further object of this invention to provide means forgenerating a low frequency acoustical signal to be propagated thru aliquid medium and a low pass filter to animal tissue for the purpose ofdetecting foreign bodies and particularly metallic foreign bodies in thetissue.

It is yet another object of this invention to provide an improved lowfrequency sound generator and receiver for locating foreign bodies inanimal tissue comprising; a housing having first and second ends, afirst rotatable member mounted inside the housing, a second rotatablemember mounted on the first rotatable member, a transducer mounted onthe second rotatable member, means for rotating the first and secondrotatable members, the transducer being moved thereby in a prescribedpattern, means coupled to the transducer causing the transducer togenerate the first and second frequencies, a cavity in the housingadjacent to the transducer, the cavity being filled with a liquidwherein the first and second frequencies interact nonlinearly, a lowpass filter mounted on the first end of the housing closing one side ofthe cavity for contacting animal tissue to be scanned and absorbing thefirst and second frequencies, a cathode ray tube mounted at the secondend of the housing, and electrical circuit means connected to thetransducer and the display means for causing the display means to depictthe position of the transducer in its prescribed pattern and to show anyecho signals received from foreign bodies in the tissue.

It is still another object of this invention to provide an improved handheld low frequency sound generator and receiver for locating foreignbodies in animal tissue by generating and receiving low frequency soundsignals and projecting the sound signals into animal tissue to bescanned wherein the necessary electronic package is mounted external tothe hand held device.

And yet a further object of this invention is to provide a hand held lowfrequency sound generator incorporating a cathode ray tube and atransducer mounted in a housing whereby a low frequency signal has agenerator and echo receiver and display on the hand held tube, wherebyan operator can conveniently move the entire device while scanningtissue.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a block diagram of one embodiment of this invention.

FIG. 2 is a cross sectional view of the mechanical construction of oneembodiment of the invention.

FIG. 3 is a view along the lines 2--2 in FIG. 2.

Generally, the operation includes first and second oscillators 10, 11coupled thru electrical means 12, 13 to an adder circuit 14. In thiscircuit the oscillator outputs are combined or summed and transmittedthru connection 15 to electrical gate circuit 16, where they are shapedinto short bursts.

Gate 16 is controlled by clock 17 thru connection 18 and the signal fromthe adders are shaped into short bursts in gate 16 wherein pulserepetition frequencies are pre-determined. The resultant multifrequencybursts are amplified in power amplifier l8 and the signal is in turncoupled to a transmit-receive switch 20 thru connection 19. The switchcontrols the flow of signal input and output and the transducer 21 isthus controlled. The received echo signal at the transducer 21 is showncoupled back to the T. R. switch 20 to a preamplifier circuit 21, thruconnection 30 to filter 31, to video amplifier 32 and display device 33.In this case the display device is a cathode ray tube. Output from apair of resolvers 34, 35 shown as a single block are connected to logiccircuit 36, amplifier 37 and to dis play device 33.

A strobic logic circuit 40 provides the ability to intensify range gatedportions of the echo field so as to present the viewer a sagittalsection of this field.

FIG. 2 is a cross sectional view of one embodiment of this inventionshowing a cylindrical housing having a rubber booted hemispherical endsection 51. The other end of the housing contains the display device,cathode ray tube 33. A shaft 54 mounted in a pair of bearings 55, 56 issupported in the housing by plates 57, 58. Mounted on plate 58 is anelectrical motor 59 driving gear 60 that meshes with gear 61 andprovides rotation to shaft 54 about an axis 62.

Shaft 54 is connected to an end plate member 63 connected thru a leg 64to a rotating plate 65.

Also mounted on shaft 54 is support plate having a bearing 71 forsupporting a second shaft 72. A gear 74 rigidly affixed to housing 50,meshes with and drives gear 75 as shaft 54 rotates about its axis.

Shaft 72 drives in a rotating manner transducer plate having transducer21 mounted therein in a circular hole in plate 65.

Slip rings 82, 83 provide the necessary electrical connection so thattransmitter-receiver switch 20 can be actuated for transmitting andreceiving the necessary signals to and from transducer 21. Resolvers orposition indicators 34 and 35 give an indication of shaft rotation andlocation in the cycle of operation so that the proper signal may bedisplayed on the cathode ray tube 33.

The portion of the device between low pass filter or boot member 51 andplates 65, 80 is a cavity 90 and it is liquid filled to couple thesignal from transducer 21 to and thru boot 51, the liquid damps out someof the high frequencies. In operation, the outside of boot 51 would becovered with a liquid such as Castor oil and placed in contact withanimal tissue to be investigated. This provides the proper coupling ofsignals back and forth. There is additionally shown an intensity control91 for convenience mounted on the device which may be hand held whileinvestigating the animal tissue.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

I claim:

1. An improved low frequency sound generator and receiver for locatingforeign bodies in animal tissue comprising:

a. a housing having first and second ends;

b. a first rotatable member mounted inside siad housing;

c. a second rotatable member mounted on said first rotatable member;

d. a transducer mounted on said second rotatable member;

e. means for rotating said first and second rotatable members saidtransducer being moved thereby in a prescribed pattern;

f. means coupled to said transducer causing said transducer to generatefirst and second frequencies;

g. a cavity in said housing adjacent to said transducer, said cavitybeing filled with a liquid wherein said first and second frequenciesundergo nonlinear interaction to produce a highly directive differencefrequency radiation;

h. a low pass filter mounted on said first end of said housing closingone side of said cavity, for absorbing the first and second frequenciesand for contacting animal tissue to be scanned;

i. a display means mounted at the second end of said housing; and

j. electric circuit means connected to said transducer and said displaymeans for causing said display means to depict the position of saidtransducer in its prescribed pattern and to show any echo signalreceived from foreign bodies in said tissue.

2. The improved low frequency sound generator and receiver of claim 1wherein said display means consists of a cathode ray tube mounted insaid second end of said housing and said electrical circuit means aremounted external to said housing and connected thereto by suitablewiring means.

3. The improved low frequency sound generator and receiver of claim 2wherein said housing is substantially cylindrical in shape and said lowpass filter is composed of a rubber booted hemispherical shaped memberfor absorbing any high frequency sound signals passing thru said liquid.

4. The improved low frequency sound generator and receiver of claim 3wherein said first rotatable member is driven by electrical means aboutthe major longitudinal axis of said housing.

5. The improved low frequency sound generator and receiver of claim 4wherein the second rotatable member is driven by a gearing meansactuated by rotation of said first rotatable member.

6. The improved low frequency sound generator and receiver of claim 5wherein there is provided first and second resolvers for indicating therelative position of said first and said second rotatable members bygenerating an electrical signal coupled to the deflection systern ofsaid cathode ray tube to provide a signal trace indicating the path ofsaid transducer.

7. The improved low frequency sound generator and receiver of claim 6wherein said liquid in said cavity consists of a nonlinear liquid.

8. The improved low frequency sound generator and receiver of claim 7wherein said electrical circuit means include a strobic logic circuit tointensify range gated portions of the echo field and is a sagittalsection of this field.

1. An improved low frequency sound generator and receiver for locatingforeign bodies in animal tissue comprising: a. a housing having firstand second ends; b. a first rotatable member mounted inside siadhousing; c. a second rotatable member mounted on said first rotatablemember; d. a transducer mounted on said second rotatable member; e.means for rotating said first and second rotatable members saidtransducer being moved thereby in a prescribed pattern; f. means coupledto said transducer causing said transducer to generate first and secondfrequencies; g. a cavity in said housing adjacent to said transducer,said cavity being filled with a liquid wherein said first and secondfrequencies undergo nonlinear interaction to produce a highly directivedifference frequency radiation; h. a low pass filter mounted on saidfirst end of said housing closing one side of said cavity, for absorbingthe first and second frequencies and for contacting animal tissue to bescanned; i. a display means mounted at the second end of said housing;and j. electric circuit means connected to said transducer and saiddisplay means for causing said display means to depict the position ofsaid transducer in its prescribed pattern and to show any echo signalreceived from foreign bodies in said tissue.
 2. The improved lowfrequency sound generator and receiver of claim 1 wherein said displaymeans consists of a cathode ray tube mounted in said second end of saidhousing and said electrical circuit means are mounted external to saidhousing and connected thereto by suitable wiring means.
 3. The improvedlow frequency sound generator and receiver of claim 2 wherein saidhousing is substantially cylindrical in shape and said low pass filteris composed of a rubber booted hemispherical shaped member for absorbingany high frequency sound signals passing thru said liquid.
 4. Theimproved low frequency sound generator and receiver of claim 3 whereinsaid first rotatable member is driven by electrical means about themajor longitudinal axis of said housing.
 5. The improved low frequencysound generator and receiver of claim 4 wherein the second rotatablemember is driven by a gearing means actuated by rotation of said firstrotatable member.
 6. The improved low frequency sound generator andreceiver of claim 5 wherein there is provided first and second resolversfor indicating the relative position of said first and said secondrotatable members by generating an electrical signal coupled to thedeflection system of said cathode ray tube to provide a signal traceindicating the path of said transducer.
 7. The improved low frequencysound generator and receiver of claim 6 wherein said liquid in saidcavity consists of a nonlinear liquid.
 8. The improved low frequencysound generator and receiver of claim 7 wherein said electrical circuitmeans include a strobic logic circuit to intensify range gated portionsof the echo field and is a sagittal section of this field.